Heat sink



FIG. 1 shows a top plan view of a heat sink.

FIG. 2 shows a left side elevation view of the heat sink of FIG. 1, the right side being a mirror image of the left side.

FIG. 3 shows a bottom plan view of the heat sink of FIG. 1.

FIG. 4 shows a front elevation view of the heat sink of FIG. 1, the back view being a mirror image of the front view.

FIG. 5 shows a top perspective view of the heat sink of FIG. 1; and,

FIG. 6 shows a bottom perspective view of the heat sink of FIG. 1.

The broken lines shown in FIGS. 3 and 6 views define the bounds of the claimed design and form no part thereof. 

I claim the ornamental design for a heat sink, as shown and described. 